Australian marine biologists conducting a study designed to save the Great Barrier Reef from being choked by weeds were surprised when these little guys started eating the evidence, as Discovery Channel reports:

A fish that gatecrashed an experiment in Australia's Great Barrier Reef has surprised scientists by emerging as an unexpected weapon against the worldwide decline of coral reefs.

Scientists from the Australian Research Council Center of Excellence for Coral Reef Studies (CoECRS) had been studying ways of reversing the effects of coral bleaching at a reef near Orpheus Island in the World Heritage listed marine park.

Part of the research involved generating a bloom of the tropical kelp sargassum weed to mimic the effects of choking invasive weeds and seeing if local weed-eating fish would chomp their way through it, said CoECRS director Professor Terry Hughes.

While herbivorous species like the parrotfish and surgeon fish only nibbled disinterestedly at the algae, the batfish (Platax pinnatus) turned up and cleared the weed within two months.

"The surprising finding ... was that a different group of fish was responsible for reversing the algal bloom," Hughes said.

"Batfish are normally considered to be plankton feeders so we were amazed when we captured on video the effects those fish were having."

Chief investigator Professor David Bellwood of the CoECRS and James Cook University said the batfish's voracious appetite for weed saved the coral from being choked to death.

"In five days they had halved the amount of weed. In eight weeks it was completely gone and the coral was free to grow unhindered," he said.